This proposal will address the commercial potential of performing cell surface marker analysis utilizing monoclonal antibodies tagged with a variety of heavy metal colloids of varying size and color. Currently cell marker analysis, proven to be clinically important in the detection, diagnosis and monitoring of human diseases, are performed either manually via fluorescent/light microscopy (imprecise identification and statistical counting errors) or by flow cytometric analysis (costly capital equipment outlay). The commercial availability of easily visualized, nonfluorescent monoclonal reagents will permit clinical hospital laboratories to perform cell marker studies on already existent capital equipment, image analysis systems, which perform routine blood cell differentials in many labs. These image analysis systems are not capable of fluorescence detection which negates their utilization with existent fluorescent monoclonals. One aspect of this project will involve the development of such nonfluorescent heavy metal colloid tags which because of their variable size and color differences may be used in combination resulting in savings to the customer. These will be coupled to a variety of commonly used and specialized monoclonal reagents against human leukocytes. This technique will permit direct visualization of the cellular elements spread in a monolayer or thin section manner on standard microscopic slides. This will permit instant cytomorphologic correlation with the cell in question. All new reagents developed will be evaluated by manual and flow cytometric methodologies in a double bind test. Once developed the reagents will be marketed for cell marker analysis using direct visual assessment (manual and/or image analysis systems) as reagents or in kit form for use in the routine clinical laboratory. A second aspect of this proposal will attempt to develop and characterize selected murine monoclonal antibodies to human tumor specific antigens. All resultant monoclonals will be carefully screened and correlated with histopathologic interpretations. The resultant monoclonals will be tagged with the new colloids and with traditional fluorescent dyes for use in manual, flow and image cytometric systems. These studies have the potential to improve the level of testing sensitivity for cell marker analysis by manual methodologies through the elimination of problems related to human (eye) detection of fluorescence intensity as the colloids are assessed by light techniques, and will afford utilization of already existent clinical lab equipment.